Pneumonia: Updates, Best Practices, and Controversies

In this clinically focused session, Dr. Joanna M Bonsall, associate professor at Emory University School of Medicine and hospitalist at Grady Memorial Hospital in Atlanta, discussed portions of the 2019 Infections Diseases Society of America (IDSA)/American Thoracic Society (ATS) community-acquired pneumonia (CAP) guidelines relevant to hospitalist practice. There was also discussion of new evidence in the diagnosis and management of pneumonia as well as some continued areas of uncertainty.

The diagnosis of pneumonia can be challenging, especially when there is an atypical patient presentation or when a chest X-ray is inconclusive. In such settings, additional imaging can help make the diagnosis. The optimal next test would be a lung ultrasound, due to the lack of radiation exposure and quick assessment by a skilled clinician. Studies have shown that sensitivity and specificity are equal to that of a computed tomography (CT) scan. However, it was recognized that this was not always readily accessible due to insufficient training or comfort in bedside ultrasound. In such cases, a chest CT is the next best test. This is probably the closest to the gold standard and can be very helpful in cases of intermediate probability.

Procalcitonin is another tool that is sometimes used to differentiate intermediate-probability cases of pneumonia. However, a meta-analysis of 2,408 patients with known CAP showed a sensitivity of 0.55, and a specificity of 0.76.¹ There are no studies that show a benefit of biomarkers versus clinical signs on antibiotic initiation in hospitalized patients with pneumonia. There is evidence demonstrating a decrease in antibiotic duration (without any clinical differences), but all studies have shown procalcitonin-guided antibiotic reduction at or above the current recommended guidelines for antibiotic duration. There may be some benefits in patients from the community, considering the prolonged antibiotic course, and it could have some antimicrobial stewardship benefits.

Molecular assays are also becoming available, although still limited in uptake. One such molecular assay, the BioFire, showed a negative predictive value from 92% to 100%, but with a positive predictive value of 5% to 100%. These do give rapid results and may give some resistance gene variants. A few small studies have shown savings and decreased antibiotic use. However, the positive predictive value is very low for the molecular assays and they do not have full representation of bacteria.

When hospitalists are faced with the decision of where to admit, it is recommended to use a validated clinical-prediction rule to determine treatment location. The Pneumonia Severity Index, or PSI, is the preferred test as it is better studied, and also tends to identify more patients as low-risk, than the CURB-65 (Confusion, Urea, Respiratory rate, Blood pressure, age 65 or older) criteria.

For determining the severity of illness for a pneumonia patient it is recommended to use the 2007 IDSA/ATS severity clinical criteria. In non-severe CAP, combination therapy with beta-lactam antibiotics and macrolide or monotherapy with a respiratory fluoroquinolone is recommended. In severe CAP, the recommended therapy is combination therapy with beta-lactam antibiotics and either a macrolide or a respiratory fluoroquinolone.

Doxycycline has been shown to be equivalent therapy to a macrolide in mild to moderate CAP. Patients who had a previous C. difficile infection had a lower risk of a recurrent infection on ceftriaxone plus doxycycline than patients who received ceftriaxone plus azithromycin.

Patients require antibiotic coverage for Pseudomonas and methicillin-resistant Staphylococcus aureus (MRSA) if they had a previous hospitalization within 90 days and/or intravenous antibiotic usage, previous infections with high-risk gram-negative rods or Staphylococcus aureus, with coordination of local risk factors to guide antibiotic usage. If initial antibiotics will cover these organisms, it’s recommended to get pretreatment sputum and blood cultures as well as a MRSA nasal swab to help with de-escalation. Otherwise in non-severe CAP without risk factors for MRSA and pseudomonas, it’s not recommended to order blood and sputum cultures.

The clinical scoring system called Drug Resistance In Pneumonia, or DRIP, showed a higher sensitivity and specificity for antimicrobial resistance than the previous healthcare-associated pneumonia, or HCAP, criteria.² This study showed using the Drug Resistance In Pneumonia score reduced the use of antipseudomonal antibiotics by 8.9% and the use of vancomycin by 16.9% compared to healthcare-associated pneumonia criteria.

The duration of antibiotics should be a total of five days for resolving CAP or for three days after clinical stability. Studies suggest that we overtreat pneumonia. One study of 6,481 patients showed that 71.8% of the patients received excessive antibiotic therapy and 93.2% completed their therapy as an outpatient. As might be expected, excessive therapy was associated with antibiotic-associated adverse events.

Recent articles have been published that may change clinical practices. One of the most significant publications described a randomized controlled trial of the use of steroids in severe CAP. Patients who received a continuous infusion of hydrocortisone of 200 mg/day for four to seven days followed by an eight- to 14-day taper had significantly lower mortality at 28 and 90 days.³ There was an increase in hyperglycemia, but no other differences in adverse events. Given the mortality benefit and low risk, it should be strongly considered to use early hydrocortisone in patients with severe CAP.

Notably, the populations that were excluded from this study included patients who had nosocomial pneumonia, were immunocompromised or had a recent gastrointestinal bleed, influenza, uncontrolled diabetes, or uncontrolled psychiatric symptoms. Another study from a few months ago looked at anaerobic coverage in aspiration pneumonia. This study excluded patients with pulmonary abscesses. It found that extended anaerobic coverage had no mortality benefit but did have an increased risk of C difficile colitis.⁴ 

Dr. Miller

Dr. Miller is an associate professor of medicine and vice-section chief of hospital medicine at the University of New Mexico in Albuquerque, N.M. 

References

1. Kamat IS, Ramachandran V, et al. Procalcitonin to distinguish viral from bacterial pneumonia: a systematic review and meta-analysis. Clin Infect Dis. 2020;70(3):538-42.
2. Webb BJ, Dascomb K, et al. Derivation and multicenter validation of the Drug Resistance in Pneumonia clinical prediction score. Antimicrob Agents Chemother. 2016;60(5):2652-63.
3. Dequin PF, Meziani F, et al. Hydrocortisone in severe community-acquired pneumonia. N Engl J Med. 2023;388(21):1931-41.
4. Bai AD, Srivastava S, et al. Anaerobic antibiotic coverage in aspiration pneumonia and the associated benefits and harms: a retrospective cohort study. Chest. 2024;20:S0012-3692(24)00260-5. doi: 10.1016/j.chest.2024.02.025.